Is Your Horse's Bit Harmful to His Mouth?

Researchers found that 62% of the domestic horse skulls examined in the current study had bone spurs on the bars of the mouth where the bit sits.

Photo: Erica Larson, News Editor

When behavioral problems arise with riding horses, owners undoubtedly will search for solutions. But many horse owners don't think to look their horse in the mouth for an answer. According to recent study results, the bit could be the cause of more behavioral problems and ailments than many owners currently recognize.

W. Robert Cook, FRCVS, PhD, completed a study recently in which he compared 66 domestic horse skulls and 12 wild horse skulls in four U.S. Natural History Museum collections for differences in structure near the point where the bit contacts the skull.

A five-point grading scale was used to document bit-induced bone spurs on the bars of the mouth (grade 1 being normal and grade 5 the most abnormal). Bone spurs are outgrowths on the bars of the mouth, akin to splints on the cannon bone. The first cheek teeth in the lower jaw are the first to be damaged due to their close proximity to the bit, so the frequency of dental damage was based on these.

Key findings of the study included:

62% of the domestic horse skulls had bone spurs on the bars of the mouth;

61% of the domestic horse skulls exhibited erosion of the first lower cheek tooth;

88% of the domestic horse skulls showed evidence of either bone or dental damage;

As the grade of bone spur formation increased from 1 to 5, so did the frequency of dental damage; and

No bone spurs or dental damage was found in any of the 12 wild horses skulls.

Cook suggests that if behavioral problems arise in riding horses, owners and trainers should consider the bit as a cause along with other possibilities. He added that a veterinarian or equine dentist can check for evidence of bit damage in a horse's mouth.

Cook, who developed and patented the crossunder Bitless Bridle, noted, "There is a simple way for an owner to find out whether any particular behavioral problem (could be) caused by the bit: Try a nonbitted bridle and see if the horse's behavior improves."

Mary DeLorey, DVM, owner of the Seattle-area based Northwest Equine Dentistry Inc., offered perspective, noting that among her patients dental abnormalities (such as tooth hooks, sharp points on molars, or periodontal disease) are more common causes of behavioral changes in the horse than bitting issues.

She estimates (unscientifically that she sees) one in 20 horses "that has some evidence of bit wear--dental attrition, most likely caused by the bit.

She explained that this bit wear is characterized by a "very smooth occlusal surface," a "beveling of the occlusal surface" on the front part of the tooth, and "discoloration of the tooth surface by the metal from the bit": "Metal is harder than dental tissues, so it will cause premature attrition of the teeth if the horse puts the bit between his teeth.

"I palpate the bars of every horse I examine," she added. "I very occasionally find bruising or lacerations to the soft tissues, usually in very young horses just beginning training. I've identified only about a dozen in the last ten years that I felt had pathologic bony changes in the bars. Only a few of these animals had any reported behavioral issues from the rider, and none were painful to palpation.

"I think there's no doubt that heavy hands or violent hands can damage a horse's mouth," DeLorey noted. "Perhaps bits designed for leverage can more easily damage the very sensitive tissues of a horse's mouth, but snaffle bits can also bruise and lacerate if used with excessive force.

"There's a lot we don't yet know about equine dentistry from a scientific standpoint," she concluded. "Having said all this, we, as horse owners and caretakers should be aware that a metal bar in a very sensitive area, applied with pressure, can certainly cause damage."

The study, "Damage by the bit to the equine interdental space and second lower premolar," was published in February 2011 in Equine Veterinary Education. The article can be viewed online.

About the Author

Casie Bazay holds a bachelor of science degree in education from Oklahoma State University. She taught middle school for ten years, but now is a nationally certified equine acupressure practitioner and freelance writer. She has owned Quarter Horses nearly her entire life and has participated in a variety of horse events including Western and English pleasure, trail riding, and speed events. She was a competitive barrel racer for many years and hopes to pursue the sport again soon.

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